On the Establishment and Maintenance of Control Surveys in Urban Areas

• Main Authors: Cheng-Wei Yen, 顏誠緯
• Other Authors: Jen-Yu Han
• Format: Others
• Language: zh-TW
• Published: 2016
• Online Access: http://ndltd.ncl.edu.tw/handle/50910346457522181656

碩士 === 國立臺灣大學 === 土木工程學研究所 === 104 === In order to manage land more efficiently, the government agencies undergo cadastral surveys to draw cadastral maps for defining the ranges of land rights. The prior task for producing figures and information with high precision to protect people’s rights and interests is to establish sophisticated results of control surveys. Owing to the mixed factors of cadastral surveys across different years, conversion of different coordinate systems, different measure approaches, and frequent public infrastructure constructions, it is not an easy task to maintain the good precision of results of control surveys in urban areas. When the quality of results of control surveys is not good, it causes errors in related results of applied surveys. Besides, in the existing mode of operations, control survey adjustments of networks are based on the assumptions that the control points are fixed and errorless, which causes the potential problems of error accumulation. The consequences of long-term cumulative errors are the gradual deterioration of control surveys.This study combined two invariant observations unaffected by coordinate system or survey methods: the relative distances and angles between surveyed points to serve as the fundamental observations for adjustment, and at the same time, the study integrated the precision of each adjustment parameter in an unified sequential adjustment for considerations. Adjustment computation in results of control surveys of building up urban areas does not only avoid the error accumulation but also shows gradual evolutionary characters. The high-quality measurements derived from each measuring task could be solved with serial approaches. Therefore, the network system can update and elevate the quality of results of control surveys step by step. In numerical experiment, verification of the feasibility could be confirmed by simulation cases, and the results of control survey project conducted by Department of Land Administration, Taipei City Government in Shilin District in 2013 is selected for case analysis to sample and test the results of unified sequential adjustment according to related norms and regulations (described as the first and the second chapters). The qualified ratio of sampling of distance is 93%; testing of angles, and sampling tests of coordinate are all 100%, which indicates that the proposed method could be integrated into the operation procedures of control network in urban areas to detect the potential problems in the evolutionary processes of network-based detection, ensure the qualities of observed data in different time periods and improve the long term stability of control network in urban areas.